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Published on January 4, 2008

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Fruit Diseases in the Home Garden:  Fruit Diseases in the Home Garden Patricia McManus Department of Plant Pathology University of Wisconsin-Madison February 2005 Fruits commonly grown in the home garden in Wisconsin:  Fruits commonly grown in the home garden in Wisconsin Apple Stone Fruits Strawberry Raspberry Grape Apple Diseases:  Apple Diseases Scab Rust Powdery mildew Fire blight Phytophthora root and crown rot Canker diseases Apple Disease Management: General Recommendations:  Apple Disease Management: General Recommendations Plant scab-resistant varieties; some of these are also resistant to other diseases. Plant in a well-drained site, preferably with light, sandy soil. Prune out diseased branches at least once per year; late winter is a good time to prune. Do not over fertilize with nitrogen. Diseases of Apple: Scab:  Diseases of Apple: Scab Cause: a fungus, Venturia inaequalis. By far the most common disease of apple and crabapple. Favored by wet weather, especially during early to middle spring. Can cause early defoliation which weakens tree, makes it less winter-hardy. Apple Scab: Symptoms:  Apple Scab: Symptoms At first, spots are velvety and olive green with indefinite margins. Can occur on upper or lower leaf surface. Apple Scab: Symptoms:  Apple Scab: Symptoms Later, spots turn brown to black; margins become more definite. Leaves turn yellow or brown; trees can defoliate prematurely. Apple Scab: Symptoms:  Apple Scab: Symptoms At first, spots on fruit similar to spots on leaves. Later, spots turn corky and brown. Spots are superficial, but can cause fruit cracking. Apple Scab: Management:  Apple Scab: Management Plant scab-resistant varieties. Remove fallen leaves in the fall and early spring before any new growth. Spray fungicides on susceptible varieties: start when leaves show 1/2 inch new growth. most garden store fungicides are protectants and must be applied before infection. if spring weather is wet, reapply fungicide every 10-14 days. Scab Fungicides:  Scab Fungicides Protectant captan ferbam mancozeb, maneb copper (e.g., Bordeaux) sulfur Systemic triforine myclobutanil fenarimol thiophanate-methyl benomyl dodine Always check the product label for permitted uses! Diseases of Apple: Rust:  Diseases of Apple: Rust Cause: fungi, Gymnosporangium species. Cedar-apple rust, hawthorn rust, and quince rust are similar but caused by different fungi. Various types of junipers (“cedars”) as alternate host. Favored by wet weather, especially around the time of bloom Rust Symptoms on Apple or Hawthorn:  Rust Symptoms on Apple or Hawthorn In the spring, spots on upper leaf surface are roughly circular and pale yellow; by mid-summer, spots are orange, sometimes with dark centers. By late summer, grayish tubes protrude from lower leaf surface. Rust Symptoms on Apple or Hawthorn:  Fruit spots similar to leaf spots; usually near bottom of fruit. Rust Symptoms on Apple or Hawthorn Rust Symptoms on Juniper:  Rust Symptoms on Juniper Brown to reddish leaf galls (up to 2 inches in diameter) which exude gelatinous, orange tendrils in the spring. Enlarged May 12 May 15 Rust Symptoms on Juniper:  Rust Symptoms on Juniper Spores produced from same lesion year after year. Quince rust forms elongated masses of short, knobby spore masses. Rust: Management:  Rust: Management Plant resistant varieties. Break the disease cycle by removing junipers that are an alternate host (not always practical!) Apply fungicides, especially during bloom. Captan and sulfur do not control rust; ferbam and mancozeb are better choices. Juniper (“cedar”) Hosts:  Juniper (“cedar”) Hosts Cedar apple rust eastern red cedar, southern red cedar, Rocky Mt. Juniper, some varieties of prostrate junipers and Chinese juniper Hawthorn rust eastern red cedar, southern red cedar, Rocky Mt. Juniper, common juniper and some varieties of prostrate junipers Quince rust eastern red cedar, Rocky Mt. Juniper, common juniper, prostrate juniper, savin juniper Diseases of Apple: Powdery Mildew:  Diseases of Apple: Powdery Mildew Cause: a fungus, Podosphaera leucotricha. Usually severe only on highly susceptible varieties (Jonathan, Rome Beauty, Cortland, Ida Red, Stayman, Baldwin). Spores do not need free water to germinate; need only high humidity at 60-80oF. Overwinters in buds; mildew infected buds more susceptible to winter kill. Powdery Mildew: Symptoms:  Powdery Mildew: Symptoms Leaves covered with white, powdery fungal growth. Later, leaves curl inward, turn brown, and die. Powdery Mildew: Management:  Powdery Mildew: Management Avoid highly susceptible varieties. If fungicides are used, start when flower bud clusters are still tightly closed; continue until terminal growth stops. Sulfur is excellent against mildew. Apple Diseases: Fire Blight:  Apple Diseases: Fire Blight Cause: a bacterium, Erwinia amylovora. Pathogen can become systemic in plant, affecting all parts. Flower symptoms favored by warm, wet weather during bloom. Young, succulent shoot tips especially susceptible. Shoot symptoms often appear about 1 to 2 weeks after a wind/rain storm. Fire Blight: Symptoms:  Fire Blight: Symptoms In winter, bark is darker than normal. Cankers sunken and cracked. Ooze is sometimes visible in spring. Fire Blight: Symptoms:  Fire Blight: Symptoms Flowers appear water-soaked, limp, and dark green to brown. After bloom, clusters remain attached and turn hard and brown to black. Fire Blight: Symptoms:  Fire Blight: Symptoms In early summer, shoot tips wilt, sometimes exude ooze. Later, shoots turn brown to black and bend back to form a “shepherd’s crook.” Fire Blight: Symptoms:  Fire Blight: Symptoms Fruit are usually brown and soft; sometimes covered with sticky ooze. Fire Blight: Management:  Fire Blight: Management Plant resistant varieties/rootstocks. Prune out affected shoots: during summer, make cuts at least 12 inches below visible symptoms; disinfest tools in solution of 1 part bleach + 9 parts water. during winter, make cuts at least 6 inches below visible symptoms; don’t need to disinfest tools. Do not fertilize with nitrogen after July 1. Apple Diseases: Phytophthora Root and Crown Rot:  Apple Diseases: Phytophthora Root and Crown Rot Cause: various species of the water mold, Phytophthora. Crown is the base of the trunk, just above where roots emerge. Only a problem if soil drainage is poor or crowns remain wet for prolonged periods. Phytophthora Root and Crown Rot: Symptoms:  Phytophthora Root and Crown Rot: Symptoms Leaves are small, yellowish, and sparse; fruit are small; often turn red prematurely. Bark and wood at crown is orange to brown and water-soaked; margin between diseased and healthy tissue is usually distinct. Phytophthora Root and Crown Rot: Management:  Phytophthora Root and Crown Rot: Management Plant in well-drained sites. Avoid heavy soils high in clay content. Do not let water pool at crown. To enhance drying at crown: control weeds and grass. do not use air-tight trunk guards. Apple Diseases: Canker Diseases:  Apple Diseases: Canker Diseases Cause: various fungi, including Botryosphaeria and Leucostoma species. Weak trees and trees under drought stress are more susceptible. Fungi often enter through pruning wounds. Apple canker pathogens are common on other woody plants. Canker Diseases: Symptoms:  Canker Diseases: Symptoms Bark becomes dark or discolored; sometimes sunken, sometimes cracked. Cankers can girdle and kill limbs, trunks, and entire trees. Canker Diseases: Management:  Canker Diseases: Management Irrigate during hot, dry periods. Prune out diseased limbs. Prune properly so that wounds heal over. Avoid trunk injury from mowers. Apply white latex paint to the southwestern side of trunks to reflect sunlight; this will prevent cracking due to expansion and contraction of bark. Calcium Deficiency in Pome Fruit:  Calcium Deficiency in Pome Fruit Common on large fruit on small trees, especially if tree is under drought stress. No pathogen involved. Bitter pit Cork spot Stone Fruit Diseases:  Stone Fruit Diseases Stone fruits include apricot, cherry, peach, and plum; some important diseases: Brown Rot Cherry Leaf Spot Perennial Canker Black Knot Virus Diseases Stone Fruit Diseases: General Comments:  Stone Fruit Diseases: General Comments Wisconsin is at the northern limit for many stone fruit trees; disease makes them even more susceptible to winter injury. Cultural practices, including good soil drainage, irrigation, and pruning will improve tree health. Disease symptoms vary on different stone fruits. Stone Fruit Diseases: Brown Rot:  Stone Fruit Diseases: Brown Rot Cause: a fungus, Monilinia fructicola. All stone fruits susceptible. Favored by humid weather at the time that fruit are ripening. Entire crop can be lost within a few days. Disease can develop on harvested fruit. Brown Rot: Symptoms:  Brown Rot: Symptoms Small, soft, brown spots expand to cover entire fruit; fungal spores appear in fluffy brown masses, especially on ripe fruit. Sour cherry Plum Tart cherry Plum Brown Rot: Symptoms:  Brown Rot: Symptoms Sour cherry Diseased fruit shrivel and harden to form mummies in which the fungus overwinters. Brown Rot: Management:  Brown Rot: Management Remove mummies after harvest and in the spring before budbreak. Fungicides (captan, triforine, myclobutanil) should be applied during bloom and again as fruit are ripening if rainy weather prevails. Refrigerate fruit after harvest. Stone Fruit Diseases: Cherry Leaf Spot:  Stone Fruit Diseases: Cherry Leaf Spot Cause: a fungus, Blumeriella jaapii. Affects sweet and sour cherry and plum. Favored by rainy weather starting at late bloom. Severe disease results in premature defoliation which makes trees less winter hardy. Cherry Leaf Spot: Symptoms:  Cherry Leaf Spot: Symptoms Reddish spots on green leaves; spots appear green, red, or brown on yellow leaves; fungal spores appear as white flecks on undersides of leaves. Lower surface Upper surface Cherry Leaf Spot: Symptoms:  Cherry Leaf Spot: Symptoms Severe disease results in early defoliation, reduced yield, and reduced tree vigor. Cherry Leaf Spot: Management:  Cherry Leaf Spot: Management In the fall or in the spring before bloom, remove fallen leaves where the fungus overwinters. If weather is rainy at late bloom and later, apply a fungicide (captan, copper) at 10- to 14-day intervals. Peach Leaf Curl:  Peach Leaf Curl Common on peach and nectarine. Similar disease (plum pockets) on plum. Can cause premature defoliation which in turn reduces tree vigor, winter hardiness. Peach Leaf Curl: Symptoms:  Peach Leaf Curl: Symptoms Leaves are thickened, curled, blistered, often reddish. Shoots are stunted. Fruit are puckered, pillow- like, reddish. Peach Leaf Curl: Management:  Peach Leaf Curl: Management Time to use fungicides is in fall or spring, BEFORE leaves emerge. Effective fungicides: chlorothalonil, copper (e.g., Bordeaux), ferbam, ziram. Where leaf curl is severe, irrigation and additional nitrogen will help maintain tree vigor. Stone Fruit Diseases: Perennial Canker:  Stone Fruit Diseases: Perennial Canker Also called Valsa canker, Cytospora canker, Leucostoma canker. Cause: a fungus, Leucostoma cincta or Leucostoma persoonii. Most severe on peach but affects other stone fruits too. Fungus enters through wounds. Can kill limbs and entire trees. Perennial Canker: Symptoms:  Perennial Canker: Symptoms Cankers form on branches, scaffold limbs, branch crotches and trunks; start out as sunken, off-color zones. Later, bark cracks and peels; gumming may occur, but this is not diagnostic. Perennial Canker: Management:  Perennial Canker: Management Prune out diseased limbs; prune properly so that wounds heal over. Avoid trunk injury from mowers. Apply white latex paint to the southwestern side of trunks to reflect sunlight; this will prevent cracking due to expansion and contraction of bark. Delay extensive pruning until spring when warm, dry weather is forecast. Stone Fruit Diseases: Black Knot:  Stone Fruit Diseases: Black Knot Cause: a fungus, Apiosporina morbosa. Common on plum and cherry, including ornamental and wild trees. Knots develop slowly, but can girdle and kill branches. Black Knot: Symptoms:  Black Knot: Symptoms Spongy and corky knots form on branches and trunk. New knots Old knots Knots older than 1 year are black and sometimes covered by white or pink fungus. Black Knot: Management:  Black Knot: Management Remove wild plum and cherry trees that may be a source of inoculum. Inspect trees several times per year for knots and prune them out making cuts 3 to 4 inches below visible knots. Fungicides applied for leaf spot or brown rot might help protect from black knot, but fungicides alone are not effective. Stone Fruit Diseases: Viruses:  Stone Fruit Diseases: Viruses Several viruses infect stone fruit trees. Wild and ornamental stone fruit trees are a reservoir. Symptoms not always visible. Leafhoppers, aphids, pollen, and dagger nematodes spread viruses. Most viruses spread through budding and grafting; some are seed-borne. Reputable nurseries screen for viruses. Virus Diseases: Symptoms:  Virus Diseases: Symptoms Sour cherry yellows (shot hole) caused by prune dwarf virus; leads to early defoliation and reduced tree vigor. Green mottle virus occurs on many stone fruits but symptoms only on sour cherry. Virus Diseases: Management:  Virus Diseases: Management Purchase certified virus-free trees from a reputable source. Destroy symptomatic trees and nearby wild stone fruit trees, even if they don’t show symptoms. Control leafhoppers and aphids. No chemical controls for virus diseases. Strawberry Diseases:  Strawberry Diseases Gray mold Anthracnose Leaf spot, Leaf scorch, and Leaf blight Black root rot Verticillium wilt Strawberry Diseases: General Recommendations:  Strawberry Diseases: General Recommendations Pathogens and diseases build up over time; renew plantings and rotate into sites where strawberries haven’t been grown. Purchase plants from a reputable source. Plant in well-drained, light soils. Irrigate early in the day to promote drying of foliage. Where possible, choose varieties resistant to the major diseases. Strawberry Diseases: Gray Mold:  Strawberry Diseases: Gray Mold Cause: a fungus, Botrytis cinerea. A common fruit rot in the field and after harvest. Favored by mild, wet weather during bloom. Gray Mold: Symptoms:  Gray Mold: Symptoms At first, tan to brown rot, often at stem end. Fluffy, gray to white fungal growth takes over entire fruit. Gray Mold: Management:  Gray Mold: Management Promote rapid drying by: maintaining narrow, widely-spaced rows running parallel to prevailing winds. irrigating in the morning for less than 2 hours at a time. controlling weeds. avoiding excessive nitrogen fertilization which promotes dense growth. Apply a fungicide during bloom, and if wet weather persists, as fruit ripen. Strawberry Diseases: Anthracnose :  Strawberry Diseases: Anthracnose Cause: a fungus, Colletotrichum acutatum. Favored by hot, wet weather as fruit develop and ripen. Can develop and spread rapidly, destroying all fruit within a few days. Anthracnose: Symptoms:  Anthracnose: Symptoms Anthracnose: Management:  Anthracnose: Management Keep soil covered with clean straw: spores bounce and spread farther off water and soil than they do off straw. Fungicides of little benefit. Almost impossible to stop an epidemic after it’s started, especially if weather is warm and wet. Strawberry Diseases: Leaf Spot, Leaf Scorch, and Leaf Blight:  Strawberry Diseases: Leaf Spot, Leaf Scorch, and Leaf Blight Three distinct diseases, but disease cycles and management are similar. Cause: fungi Mycosphaerella fragariae, Diplocarpon earliana, and Phomopsis obscurans. All favored by wet weather. If severe, reduce plant vigor and winter hardiness. Strawberry Leaf Diseases: Symptoms:  Strawberry Leaf Diseases: Symptoms Leaf blight: red-brown spots; often V-shaped at base Strawberry Leaf Diseases: Angular Leaf Spot:  Strawberry Leaf Diseases: Angular Leaf Spot A bacterial disease; symptoms often show on only one half of a leaflet; spots are delimited by small veins. Leaf Spot, Leaf Scorch, and Leaf Blight: Management:  Leaf Spot, Leaf Scorch, and Leaf Blight: Management At harvest, mow with blade set high; rake leaves and remove from the area. Irrigate early in the day to promote drying of foliage. Purchase plants from a reputable source. Where possible, choose varieties resistant to leaf diseases. Strawberry Root Diseases:  Strawberry Root Diseases Black root rot (complex of factors) and red stele (Phytophthora fragariae). BRR and RS common in Wisconsin, especially where soils are heavy. No chemical control or resistant varieties for BRR; resistant varieties for RS. Black Root Rot Symptoms:  Black Root Rot Symptoms Root system smaller than in healthy plant. Main roots have dark lesions. Small feeder roots dark and brittle or absent. Black root rot Healthy Red Stele of Strawberry:  Red Stele of Strawberry Foliage stunted. Feeder roots lacking. Central core (stele) of root is brick red rather than white. Strawberry Root Diseases: Management:  Strawberry Root Diseases: Management Provide adequate soil drainage. Avoid planting in heavy, compacted soil. Consider raised plantings in heavier soils. Protect plants during winter with adequate straw cover. Renew plants and rotate into sites where strawberries have not been grown. Strawberry Diseases: Verticillium Wilt:  Strawberry Diseases: Verticillium Wilt Cause: fungi, Verticillium species. Favored by alternating cool and warm days. Verticillium infects many fruit, vegetable, and ornamental plants and remains in the soil for many years. Verticillium invades water-conducting tissue. Diseased plants generally die. Verticillium Wilt: Symptoms:  Verticillium Wilt: Symptoms In older plantings, outer leaves wilt, turn yellow to brown at margins and between veins. In new plantings, dieback appears when runners form. Verticillium Wilt: Management:  Verticillium Wilt: Management Purchase plants from a reliable source. Choose resistant varieties. Allow 3 or more years after growing tomatoes, peppers, eggplant, potatoes, strawberries, or raspberries before rotating to strawberries again. Raspberry Diseases:  Raspberry Diseases Anthracnose Spur Blight Verticillium Wilt Phytophthora Root Rot Virus Diseases Raspberry Diseases: General Recommendations:  Raspberry Diseases: General Recommendations Purchase certified virus-free plants from a reputable source. Destroy wild or abandoned bramble plants in the area. After harvest, remove canes that have fruited and any diseased canes. Improve air circulation by pruning and controlling weeds. Raspberry Diseases: Anthracnose:  Raspberry Diseases: Anthracnose Cause: a fungus, Elsinoe veneta. Black and purple varieties more susceptible than red varieties. Severe disease makes canes less winter hardy. Anthracnose: Symptoms:  Anthracnose: Symptoms Spots start out with purple borders and gray or tan centers. Anthracnose: Symptoms:  Anthracnose: Symptoms By late summer, spots are large, more tan than purple, coalesce to form “gray bark.” Raspberry Diseases: Spur Blight:  Raspberry Diseases: Spur Blight Cause: a fungus, Didymella applanata. Common on red and purple varieties but not black varieties. Severe disease makes canes less winter hardy. Spur Blight: Symptoms:  Spur Blight: Symptoms Bluish-brown or purplish-brown cankers develop at spur where a leaf is attached. Symptoms usually on lower portion of cane; worse in dense plantings. Anthracnose and Spur Blight: Management:  Anthracnose and Spur Blight: Management After harvest, remove canes that have fruited and any diseased canes. Improve air circulation by pruning and controlling weeds. Delayed dormant application of lime-sulfur helps reduce inoculum. Raspberry Diseases: Verticillium Wilt:  Raspberry Diseases: Verticillium Wilt Cause: fungi, Verticillium species. Favored by cool spring weather; symptoms arise during hot, dry weather. Usually worse in black and purple varieties than red varieties. Verticillium infects many fruit, vegetable, and ornamental plants and remains in the soil for many years. Verticillium invades water-conducting tissue. Verticillium Wilt: Symptoms:  Verticillium Wilt: Symptoms Lower leaves are dull rather than bright green. Higher up on stem, older leaves turn yellow, shoot tip wilts, and cane may collapse. Blue streaks on the surface of canes; red to brown streaks in the vascular tissue. Verticillium Wilt: Management:  Verticillium Wilt: Management Purchase plants from a reliable source. Allow 3 or more years after growing tomatoes, peppers, eggplant, potatoes, strawberries, or raspberries before rotating to raspberries again. Remove symptomatic plants, including roots, as soon as they are noticed. Raspberry Diseases: Phytophthora Root Rot:  Raspberry Diseases: Phytophthora Root Rot Cause: various species of the water mold, Phytophthora. Only a problem if soil drainage is poor or crowns remain wet for prolonged periods. Diseased plants are susceptible to winter injury. Phytophthora Root Rot: Symptoms:  Phytophthora Root Rot: Symptoms Plants are generally unthrifty and lack vigor; leaves are small and yellowish. Crown/root tissue soft and reddish instead of green- white; sharp margin between healthy and diseased tissue. Phytophthora Root Rot: Management:  Phytophthora Root Rot: Management Plant in well-drained sites with light soil. If drainage is a problem, plant in raised beds. Fungicides only marginally effective; will not restore vigor to declining plants. Raspberry Diseases: Viruses:  Raspberry Diseases: Viruses Cause: various viruses which are carried by aphids or nematodes. Viruses more common in raspberry than other fruit plants. Wild brambles are a reservoir for viruses. Can significantly reduce yields. Symptoms can be confused with injury from herbicides or insects. Tomato Ringspot Virus Symptoms on Raspberry:  Tomato Ringspot Virus Symptoms on Raspberry Symptoms vary depending on variety and time of year. Can be general stunting and bronzing. Can be vein chlorosis, ringspot on leaves, and crumbly berries. Raspberry Leaf Curl Virus Symptoms:  Raspberry Leaf Curl Virus Symptoms Small leaves that are cupped downward and inward; fruit can be small, plants stunted. Raspberry Virus Diseases: Management:  Raspberry Virus Diseases: Management Purchase certified virus-free plants from a reputable source. Remove diseased plants and wild brambles. Control aphids. No chemical controls for viruses. Grape Diseases:  Grape Diseases Black Rot Downy Mildew Powdery Mildew Phomopsis Cane and Leaf Spot Grape Diseases: General Recommendations:  Grape Diseases: General Recommendations Relatively few important diseases, but these can cause severe losses. Vitis labrusca (American) much more disease resistant that Vitis vinifera (European). Purchase certified virus-free plants from a reputable source. Improve air circulation by pruning and controlling weeds. Grape Diseases: Black Rot :  Grape Diseases: Black Rot Cause: a fungus, Guignardia bidwellii. Most economically important grape disease in the Midwest. Can cause total crop loss if wet weather prevails. All succulent new growth--leaves, stems, tendrils, and fruit--is susceptible. Black Rot Symptoms:  Black Rot Symptoms Leaf spots are tan and irregular in shape, have dark borders, and develop black fungal fruiting bodies. Black Rot Symptoms:  Black Rot Symptoms Fruit spots are small and white with tan margins; later they expand, turn brown,and whole berries shrivel, turn hard, and become spotted with fungal fruiting bodies. Black Rot: Management:  Black Rot: Management Remove mummies (dried-up diseased fruit) in the fall or spring before budbreak. American grape varieties more resistant than French hybrids. Prune well to open canopy and improve air circulation. If fungicides are used, early spring applications are most important. Grape Diseases: Downy Mildew:  Grape Diseases: Downy Mildew Cause: a water mold, Plasmopora viticola. Favored by cool, rainy weather. Symptoms usually not visible until middle or late summer. Direct losses due to rotting of flowers and fruit. Early defoliation can make vines less winter hardy. Downy Mildew: Symptoms:  Downy Mildew: Symptoms Leaf spots are yellowish on upper surface, white and downy on lower surface. Late-season infection results in a mosaic of yellow, red, and brown angular spots. Early symptoms Late symptoms Downy Mildew: Symptoms:  Downy Mildew: Symptoms Diseased fruit are off-color, shrivel and become covered with white, downy fungal growth. Downy Mildew: Management:  Downy Mildew: Management American varieties more resistant than French hybrids and vinifera varieties. In the spring before budbreak, remove dead leaves from the previous season. Prune well to open canopy and improve air circulation. Grape Diseases: Powdery Mildew:  Grape Diseases: Powdery Mildew Cause: a fungus, Uncinula necator. Favored by warm, humid weather (but not heavy rains). Reduces vine growth, fruit quality, and winter hardiness. Many plants get powdery mildew, but in general, each plant species has a unique mildew species. Powdery Mildew: Symptoms:  Powdery Mildew: Symptoms Ohio State University Extension White, dusty fungal growth appears on upper and lower leaf surfaces. Young leaves become distorted and stunted. Fruit skins are dry, tough and cracked. Powdery Mildew: Management:  Powdery Mildew: Management American varieties more resistant than French hybrids. Prune well to improve air circulation within the canopy. Sulfur is an effective mildewcide, but certain varieties (e.g., Chancellor, Concord, and Foch) are sensitive to sulfur, especially at temperatures >85o F. Grape Diseases: Phomopsis Cane and Leaf Spot:  Grape Diseases: Phomopsis Cane and Leaf Spot Cause: a fungus, Phomopsis viticola. Formerly known as “dead arm.” Fruit usually not affected directly. Canes with severe lesions more prone to wind damage. Disease most active in the spring and fall during rainy weather. Phomopsis Cane and Leaf Spot: Symptoms:  Phomopsis Cane and Leaf Spot: Symptoms Canes, shoots, and petioles (especially lower portions) have brown to black blotches that coalesce; leaf symptoms include small, chlorotic spots with dark centers, leaf puckering, and necrosis along veins. Phompsis Cane and Leaf Spot: Management:  Phompsis Cane and Leaf Spot: Management Prune out and remove any diseased canes. Fungicides most effective in the spring when new shoots are 1 to 3 inches long; if wet weather prevails, apply again when shoots are 4 to 6 inches long. Further Information:  Further Information Your county Extension office has several bulletins in stock and a catalog of the entire inventory. American Phytopathological Society (APS) Press produces a “Disease Compendium” for apple, stone fruits, strawberry, raspberry, grape, and several other crops and ornamental plants. These are approximately $40 each. Call 1-800-328-7560. Internet: www.scisoc.org/apspress. Further Information:  Further Information Some good web sites: http://cecommerce.uwex.edu/ www.caf.wvu.edu/kearneysville/wvufarm1.html www.nysaes.cornell.edu/pp/extension/tfabp/

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